when to use react useeffect code example

Example 1: useeffect react

useEffect(() => {
	//  code goes here
    return () => {
      // cleanup code codes here
    };
  },[]);

Example 2: how to setstate in useeffect

React.useEffect(() => {
  let didCancel = false;
 
  // ...
  // you can check didCancel
  // before running any setState
  // ...
 
  return () => {
    didCancel = true;
  };
});

Example 3: react useeffect

import React, { useState, useEffect } from 'react';
function Example() {
  const [count, setCount] = useState(0);

  // Similar to componentDidMount and componentDidUpdate:  useEffect(() => {    // Update the document title using the browser API    document.title = `You clicked ${count} times`;  });
  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}